Hello, i have a seagate hard drive it shows up correct, but in your case have you tried contacting seagate or tried re-installing if possible?
Hope this helps,
I recently upgraded from XP to Vista, once I did my 320GB Seagate HD only shows up as having 120GB of space in Vista. BIOS recognizes it as 320GB, I have tried numerous things. Please help anyone. Thank you.